24-10-2019, 10:24 PM
I agree with Zetomagneto. As I said, it's to do with the fact that the points should open at magnetic flux peak on the primary side and this is internally timed to be when max advance is set up.
According to Nicholson (P171, 2nd ed, The Gregg Publishing Co. Ltd. London 1928)
"The reason why coil ignition is more sensitive to advance and retard adjustments lies in the fact that the magneto spark is automatically advanced with increase of its armature speed, whereas the coil spark is - so to speak - stationary as regards the movement of its occurrence in relation to piston movement. For the reasons given, it is essential that the ignition lever should be well retarded in starting on the coil - particularly when the engine is stiff - as it is when new or in cold weather: otherwise you are quite likely to get a backfire, which will work either against you or the starter, at the risk of injury to one or the other."
I also don't start my mag engine car on the handle because:
a) It's hard work.
b) It has a perfectly good starter motor.
c) The starting handle shaft dog end is worn and is likely to slip on the engine dog.
According to Nicholson (P171, 2nd ed, The Gregg Publishing Co. Ltd. London 1928)
"The reason why coil ignition is more sensitive to advance and retard adjustments lies in the fact that the magneto spark is automatically advanced with increase of its armature speed, whereas the coil spark is - so to speak - stationary as regards the movement of its occurrence in relation to piston movement. For the reasons given, it is essential that the ignition lever should be well retarded in starting on the coil - particularly when the engine is stiff - as it is when new or in cold weather: otherwise you are quite likely to get a backfire, which will work either against you or the starter, at the risk of injury to one or the other."
I also don't start my mag engine car on the handle because:
a) It's hard work.
b) It has a perfectly good starter motor.
c) The starting handle shaft dog end is worn and is likely to slip on the engine dog.